How Antidepressants Are Supposed to Work to Relieve Pain
Antidepressant drugs are typically prescribed for treating depression, but they’re also used for pain relief, especially for chronic pain conditions. Although the exact mechanism by which antidepressants alleviate pain is not fully understood, various theories have been proposed.“While many mechanisms of action are theorized, including specific activity and action anywhere between the peripheral and central nervous system, these drugs may be effective by restoring some degree of normal nervous system function to baseline,” Dr. Kevin Zacharoff, a chronic pain and substance use expert, Clinical Instructor, and the Course Director of Pain and Addiction at the Renaissance School of Medicine at Stony Brook University, told The Epoch Times.
“It is possible that these drugs are effective by restoring some degree of normal nervous system function to baseline.”
Zacharoff emphasized that antidepressants are typically prescribed as an adjunct pain treatment. “This means medications which can be used to enhance the effects of pain medications, treat concurrent symptoms, and provide analgesia for other types of pain,” he said. “In this context, which would generally mean in addition to more traditional medications, such as opioid analgesics, nonsteroidal anti-inflammatory drugs, or acetaminophen,” he added.
Zacharoff also said that patients with chronic pain might experience varying degrees of coexisting anxiety, depression, or other mental health symptoms that could potentially benefit from the inclusion of an antidepressant in their pain management plan.
Only 1 Drug Showed Effectiveness
A two-year review of prior studies conducted by the non-profit group Cochrane analyzed 176 trials involving nearly 30,000 participants undergoing treatment for three primary types of chronic pain: fibromyalgia, nerve pain, and musculoskeletal pain. The review encompassed a wide range of 25 different antidepressant medications.- Citalopram, a selective serotonin reuptake inhibitor (SSRI), and amitriptyline, a tricyclic antidepressant. Both medications treat neuropathic pain, which is chronic pain caused by nerve damage.
- Fluoxetine, which is used to treat nociceptive pain. It originates from tissue damage caused by physical or chemical causes such as surgery or chemical burns.
- Paroxetine, which is commonly prescribed as an adjunct medication for bipolar disorder, but is also used for the treatment of chronic headaches, as well as the management of symptoms like tingling, pain, or numbness in the hands and feet.
- Sertraline, which is usually prescribed to alleviate symptoms of obsessive-compulsive disorder and has also been shown effective in one of the studies reviewed for the treatment of noncardiac chest pain and chronic pelvic pain.
- Duloxetine, which is prescribed to manage major depressive disorder and generalized anxiety disorder. The medication also treats fibromyalgia, diabetic peripheral neuropathy, and chronic musculoskeletal pain.
However, despite this expectation, the review found little evidence to support this notion.
Nonetheless, one antidepressant showed promise in providing short-term pain relief.
“We did find that duloxetine provided short-term pain relief for patients we studied, [but] we remain concerned about its possible long-term harm due to the gaps in current evidence,” Pincus said.
The review also found that duloxetine was consistently the highest-rated medication, demonstrating equal effectiveness in treating fibromyalgia, musculoskeletal pain, and neuropathic pain. Furthermore, researchers concluded that standard doses of duloxetine appear to be as effective in reducing pain as higher doses.
Did Researchers Find a Lack of Effectiveness or Lack of Evidence?
According to Sullivan, the evidence regarding the effectiveness of other antidepressants, whether in the short or long term, was not strong enough to draw definitive conclusions.Zacharoff explained that the Cochrane review of studies aimed to assess the scientific evidence supporting the benefits of antidepressant therapy in managing chronic pain in adults. “This review did not yield a significant amount of evidence for them in the majority of cases,” he said.
But, Zacharoff pointed out, this lack of evidence does not necessarily mean that antidepressants have no beneficial effect as adjuvant therapeutic agents for chronic pain. They might still be helpful for “people who have chronic pain along with anxiety and/or depression, which might be a significant number of people,” he noted.
Adults with fibromyalgia, which is long-lasting pain throughout the body, are more than three times more likely to have major depression than those without the condition, according to the U.S. Centers for Disease Control and Prevention (CDC).
What this means for patients, according to Zacharoff, is that a patient-centered and individualized pain treatment plan should take into account the potential benefits of adding an antidepressant medication, considering the specific context of each patient, including coexisting medical conditions and other risk factors.